Hi Dale, you can use any device that creates a LAN-to-LAN connection between main office and Office2. I would go for a 871 router or a PIX 506E.
But, why not having a VPN device on the Office2 and the users to connect using VPN client from Site1 directly to Office2, and not through main office. A PIX 506E on Office2 will do the trick.
Please rate if this helped.
Regards,
Daniel